Prep Photos Laser Engraving

8/10/2019 Prep Photos Laser Engraving

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Prepar ing Pho tos

for Laser Engraving

Epi log L aser

16371 Table Mou ntain Parkway

Gold en, CO 80403303-277-1188 -vo ice

303-277-9669 - fax

www.epi loglaser .com


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Lasering Photog raphs November 2008

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Tips for Laser Engraving Photographs

There is a lot of interest in laser engraving photographs, but sometimes users getdiscouraged when they cant produce the same quality images with their machines thatthey see on display at trade shows. The following information will provide somestrategies for experimenting with photos so that you can become comfortable laseringphotos for your clients. Keep in mind that there is no one correct method of engravingphotos. A lot of it is personal preference learned through experimentation, but there area few techniques that virtually anyone who laser engraves photos will find useful.

Give these strategies a try. Weve tried to break down the process into small, easy tounderstand concepts, that can be used individually or grouped together. When youre

going through the instructions, make your own notes and keep samples that you like soyou can refer to them the next time you engrave a photo. These notes and samples willbe a great resource to you in the future!

Dont worry about becoming an instant expert. Try one thing at a time. Takenindividually, these concepts are pretty easy to follow, and once you understand theindividual concepts, putting them together becomes quite easy!

Gett ing Started- The first thing you should do if you are new to photo engravingis set aside some quiet time to practice and get familiar with the process. Thereare probably some concepts here that are new to you, so it will be beneficial to

try some of these ideas without distraction.

Different Materials- A single photo is going to engrave differently from onematerial to the next. Many users like to use black marble for their photos. Blackanodized aluminum, black plastic, clear acrylic, and wood are also popularmaterials, but they all engrave differently and you will need to compensate for thematerial.

Ar twork Not all photos are going to engrave well. Photos that laser best arephotos that contain a wide range of light to dark shades and everything in-between. Photos with large areas of a single color typically do not engrave well

especially when working with wood.


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Software Virtually any graphics software has the ability to modify ascanned or digital photo to work with the engraver. This tutorial addressesonly CorelDraw and Corel Photo-Paint version X4, but the principles andtools apply to other packages such as Photoshop, etc.

There are third party software packages available that are designedspecifically for preparing photos for laser engraving: PhotoGrav andCadLinks EngraveLab called PhotoLaser are two of the more popular.These software packages cost $400 to $500 and have some nice featuresthat may make your photo manipulation easier than using Corel alone.

PhotoGrav or PhotoLaser are designed to make the photo process amatter of a couple of mouse clicks instead of going through the processeslisted in this paper.

Engraving Resolut ion Most photos look better if they are engraved at lower

resolutions than standard engraving projects. Resolutions of 200, 300 or 400 DPIare commonly used. The resolution that you use for engraving is important toknow before you start the manipulation process because some of the processesused to manipulate a photograph are resolution dependent. Because of this, andbecause most users engrave photos at 300 DPI, all of our processes are going toassume that we are going to engrave at 300 DPI. But dont worry too much aboutthis. Its nice to know that there is a difference, but its also doubtful that you oryour customers will be able to tell if you processed a photo at 300 DPI andengraved it at 200 DPI.

Dot Gain - Taken together, the adjustment of the variables discussed above

(material, the photo, engraving resolution) can be grouped together and given aterm thats familiar in the printing industry dot gain. What were really doingwhen we adjust a photo is just adjusting the number and spacing of the dots toproduce an image that is pleasing to the eye. Since different materials handledots differently, we need to take that into account by adjusting the dot gain

Although for laser engraving, were almost always trying to reduce the number ofdots, we almost never try to gain dots.

If you try to think about processing a photo for laser engraving as reducing thenumber and spacing of dots it may help make your life easier when engravingphotos.


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Table of Con tents

Determining the suitability of a photo for engraving

Acquiring a photo Cropping

Crop Tool Cutout Lab Mask Tools Creating a Vignette Place Inside a Container

Sizing

Softening the Intensity of a Photo

Adjusting contrast and brightness

Inverting a photo

Converting to 1-bit

Printing

Photo murals on tile


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Determ ining the sui tabi l i ty of a pho to for engraving

There are several considerations that need to be taken into account whendetermining whether a photo is suitable for engraving:

o Ideally a photo will show many gradations of color from light to dark.o The photo will show good focus and definition of detail.o The photo should have good contrast and focus.o It should be interesting. By this we mean that it should have a number of

different elements to look at. In the photo below the hands break up theface and hair and the face itself is nicely shaded with features that arevery distinct.

o In contrast to the photo above, the next photo is not as suitable forengraving.

This photo is excellent

for lasering because

most of the photo is a

gradient pattern of light

to dark. There is not

much in the way of bigblocks of color and there

is a lot of detail to make

the photo really pop

when lasered.


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This photo will only engrave well

if the black background is taken

out. Leaving the background

intact will detract from the

engraving by producing a largearea that contains nothing to

look at.

With that said, this photo can

actually be saved with a little

processing that we will show

later on, but in general, photos

with large blocks of

uninterrupted color will not

engrave well without some

manipulation.


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Acqui r ing a Photo

Either scan an actual photograph, or download a photo from a digital camera.o Scanning Resolution Scan your photos at the resolution you plan using for

engraving. If youre going to engrave at 300 DPI there is no reason to scan at ahigher resolution.

o Color or B/W Scan your photos in color mode if possible. You can even scan ablack and white photos in most scanning software. There are subtle advantagesto using color that will be explored later.

o Digital images- Make sure you get the highest resolution digital image you can.Low resolution photos from the Internet are almost never suitable for engraving.If you look hard you can occasionally find high resolution graphics on theInternet, but the vast majority of images are low res and too small in size to be

useful.o Size- Get the largest size image available. Simply stretching a photo in Corel is

going to reduce the resolution of the image and if the photo is stretched too far,the photo will become too pixilated to engrave. We will show how to properlystretch a photo later on.


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Cropping

Depending on the photo and the project there are a variety of ways to crop aphoto. This part of the tutorial will show several techniques that are commonlyused.

The simplest method is to use the Croptool in Corel.

Select the Croptool, click and drag your mouse across the area you want to protectand then release your mouse. Double click in the protected area and thats all there is toit. The Croptool only allows you to crop a rectangular area, but it is a very useful toolfor many applications.


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Cutout Lab

Sometimes cropping involves getting rid of an irregular area of the photograph. Corel

Photo-Paint provides a very simple tool to do this. Either open Corel Photo-Paint orselect the photo in CorelDraw and click on the Edi t Bi tmapsbutton in Corel:

IN Photo-Paint, go to Image, and then click on Cutout Lab.

Clicking the Edi t Bi tmapsbutton takes your photo directlyinto Corel Photo-Paint.


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Were going to use a different photo to show how to use Cutout Lab to crop out the bigdark area of a photo that we know will not engrave well.

Use the Highl ighter Tooland trace around the outside edge of the area you want to

keep. Notice that you can change to size of the Nib. This helps to easily define the areayou are going to crop.

After outlining the photo, use the Inside Fi l ltool and click anywhere inside the area thatyou want to keep.

Click on Previewto see your results.

Inside Fi l lTool


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After clicking onPreviewyou can usethe Add Detai ltool orthe Remove Detailtool

to fine tune your photo.

After using the Addand Remove filltools to refine thecutout, the photolooks much betterand is ready foruse.

Click Okayto viewthe finished photo.Save the finishedphoto form Photo-Paint and import itinto CorelDraw.


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You now have acropped photo

thats ready touse.


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Mask Tools

Photo-Paint offers a number of tools that allow you to crop in many different ways.These tools are called the Mask tools and are found in the Masktool fly out:

The Masktools require a little

more effort to use, but it is worththe time to look into them.

You will gain an understandingof how they work when we usethe El l ipsetool in the nextsection.


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Creat ing a Vignet te

A vignette is an image that has been cropped in a way that produces a soft featherededge to the area being cropped. This is a little more involved method of cropping, butthe effects created are very pleasing.

Its necessary to carefully follow the order of these next steps. Until you gain anunderstanding of what the steps do, following them in order will make this a very easytask.

First, open a photo in Photo-Paint, or select a photo in CorelDraw and use the EditBitmap button that we used earlier. The next step is to setup Photo-Paint so you canmodify the photo.

Thats all the set up you have to do.

Next, select the Ell ipse Masktool from the Tool Bar. Mostusers use the El l ipsebecauseit provides a nice oval withwhich to frame the face.

First, Click on the Maskmenuand make sure both MaskOverlayand Marquee Visibleare activated (they should havea check next to them).

With the Marquee tool selected,your marquee tool options willappear. Click on the NormalMode tool (next to the wordMode .

Set your Feather MaskWidthto 99.


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At this point were ready to select the area we want to keep and create our vignette.Move your Ellipse Marquee Tool to a starting point on the photo and click and holddown the mouse. Then, drag a circle (ellipse) across the face in the photo. Move yourmouse around until the marquee defines the area you want to keep and then releasethe mouse.

Photo-Paint does not allow you to easily change the selected area. One of the easiestways to select the area you want is to start from the middle and hold the shift key whileyou drag your mouse. This will generate a marquee from the center. Practice a coupleof times until you get used to it.When you release your mouse, the mask will show up.

Notice that the oval around the face is fuzzy. This is a result of setting the Feather valuefrom the previous page to 99. If you want a sharper edge, you can lower the feathervalue and redraw the mask, or, if you like where the mask is, go to the Maskmenu,Mask Out l ine, Featherand the Feather dialog box will appear.

The mask shows up as anorange overlay. Its important tounderstand that everythingunder the orange overlay Maskis protected and cannot bemodified. This will be importantfor some applications later on.


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Once you have the vignette the way you want it to look, youre ready to delete thebackground and save the image.

To delete the background area we need to invert the mask. Remember that everythingunder the mask is protected. Now well protect the face, and delete the background.

To invert the mask and protectthe face, just click on the InvertMaskbutton.

Alternatively, from the Maskmenu, click on Invert.

Now the maskshows the areathat willbecome ourvignette.

Use the Featherbox to makeadjustments to the mask.Double click on the eye icon toview your changes.


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To delete the background, click on the Filltool (the little paint bucket):

Move the Filltool anywhere on the photo and press the Delete key on your keyboard.

Your photo will now look like this:

You can now save the photo as a .bmp and then import it back into Corel. Its ready forlaser engraving!

Thats it! You have quickly andeasily eliminated thebackground and you now havea lovely photo with softfeathered edges ready forengraving.


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The only setting you may need to change is when you delete the background.

After clicking OK, go back to your photo and then select the Filltool again and pressDelete. That should give you a white background and you can now save the photo.

You may need to change yourbackground color so that whenyou press the Delete key youcreate a white background.When you press Delete and itcreates a background otherthan white, press Ctrl Z to undothe Delete.

Double click on the twooverlapping squares that are

the Background color icon.Dont click on the single square.

You should get the ForegroundColor window. Move the sliderbar all the way to the top tochange your Background colorto White. Once you move theslider bar up to the top, theName will change to White.Click on OK.


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Cropp ing w ith the Place Insid e Container PowerClip tool

There is one more method of cropping that is popular. This is done in CorelDraw and isvery easy to perform.

For this example we are going to place a photo in an irregularly shaped object apentagon.

First, place the object over the area of the photo that you want inside the object.

Next, select the photo and click on Effects, PowerCl ip, Place Insid e Container

You will see a large black arrow

.Use the arrow to click on the outline ofthe container object. You may have tozoom in to select the container.


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You have now cropped a photoinside a container. You can usea container of any shape you

can create.


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Sizing

Now that youve cropped your photo and its in the form you want to use, we can nowsize it.

The photo below was downloaded from a digital camera. This sizing process is usefulfor any photo whether it was acquired from a camera, was scanned or came from theInternet. Weve imported the image below into Corel and we want to engrave this photoonto a plaque. As you can see, its about the same size as the plaque, so we need toshrink it. For most objects in Corel you would grab one of the corner handles and shrinkor expand until it looked good. With a photo we need to take more care.

o Before sizing the photo, make a duplicate of it first and move it to the side.Because were going to manipulate the photo its always good to have theoriginal close at hand so we can start over if we want to.

o Decide on the size the photo needs to be. Select the photo and use one of

the corner handles to determine the appropriate size. Make a note of thesize you want the photo to be after shrinking and then use Ctrl Z to undo itback to its original size.


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You should be able to see the size and location of the photo in the upperleft corner of Corel. The following screen shot from Corel shows that thesize we want the photo to be is 3.125 x 2.528.

o Were now ready to size the original photo. Select the original photo and click onBitmaps | Resamplein the Corel menu bar.


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The Resamplewindow comes up and, as you can see, there are two mainparameters that can be changed; Size and Resolution.

Input the size (3.125 x 2.528) that we want the photo to be.

After setting the size, set the resolution. Since were going to engrave using 300DPI, set the resolution here to 300 x 300.

Click OK and you will go back to your Corel Page.

Its usually advisable tomake sure Maintainaspect ratioisselected. You will seein the next screen shotthat this forced theHeight to be a veryslightly different size,but the difference is sosmall (0.006 inch) youwill never notice it.


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Notice that we now have a photo that fits the plaque with the original photo off to theside.


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Softening the Intens ity of a pho to

It is frequently the case that the photographs you want to engrave get washed outbecause they are too intense for the laser. This is because most photos are designed tobe exceptionally high quality images and there is a lot more information than can beprocessed in a 300 DPI engraving.

This process can be performed before or after cropping and sizing with the exception ofa photo inside a container. For this one process you will need to soften the photo beforeplacing it in the container.

To soften a photo we want to just lighten it so it doesnt look washed out whenengraved. You can do this in Corel or Photo-Paint.

You need to make sure the photo is in the correct format before you can adjust theintensity. In Corel, select the photo and go to Bi tmaps. If the Image Adju stment Labisgrayed out, you will need to click on Convert to Bi tmap

Set the Resolution to 300 DPIand the color mode to RGBColor (24 bit), and then clickOK. This will convert your phototo a mode that can be adjusted.


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Select the photo again and go back into the Bi tmapsmenu.

Click on Image Adju stment Lab.

The Image Adju stment Labhas a number of settings thatcan be changed. Usually, justchanging the Br ightnessandContrastare enough to softenthe photo.


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Usually increasing the Brightness (we increased it to 30) and decreasing the Contrast(we decreased it to -20) is all that is needed. The photos below show the before andafter effects.

Before adjustment After adjustment


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Invert ing a Pho to

If you are engraving a photo on dark material like black marble or black anodizedaluminum you are going to need to invert the photo before sending it to the engraver.Inverting is nothing more than converting it into a negative; although this can causecomplications if you decide you want to invert the photo after all of your otheradjustments have been made.

It s usu al ly b est to inver t the pho to in the ear ly stages of p rocessing,

so take the mater ial you are going to engrave on into acco unt b efore

you begin!

Many users have difficulty with negatives until they try it out a couple of times, so itshelpful to know how the laser works if you need to think about a negative (inverted)

image. The way the laser works is that it fires wherever there is a dot in the artwork. Formost engraving materials like wood or acrylic you are creating a dark mark wherever thelaser hits the material. On material like black marble you are doing the opposite youare creating white wherever the laser fires, not dark. Inverting just changes all of theblack dots to white and vice-versa.

Inverting a photo is quite easy. In Corel, select your photo and then go to Effects,Transformand Invert.


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In Photo-Paint go to the Imagemenu, Transform, and then Invert.

As you just saw, inverting is easy if you have not created a vignette or other boundaryaround the photo. If you have created a boundary you will run into the problem wherenot only is the photo inverted, the background is inverted as well.

To see what this means, lets look at a photo that was inverted before applying anyprocesses and compare that to one that was inverted after all processes were complete.

All of the steps were the same. The only difference was when the image was inverted.

Before Inverting After Inverting

Inverted beforeprocessing

Inverted afterprocessing


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As you can see, there is quite a difference. To prevent this from happening is easy ifyou know you are going to need an inverted image. We will use the vignette to show theprocess when processing your photo.

In Photo-Paint use the Masktool to create your mask area.

This is where we want to invert the image. To invert, go to the Imagemenu, Transform,and then Invert.

The face has now beeninverted.

At this point you will probablywant to adjust the intensity of thephoto like we did in the previoussection. Even though the imageis now a negative, the processwill be the same.


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Notice that there is a lot less black in the photo after modification. The image on theright will engrave onto black marble or anodized aluminum much better than the image

on the left.

In the Image Adju stmentLab, increase theBr ightnessand decreasethe Contrast.

Whether your image is anegative or positive, whatyoure looking for in theImage Adju stment Labisan image that has a lot ofgray in it.

Before modification inImage Adjustment Lab

After modification in ImageAdjustment Lab


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At this point, your image is cropped and sized and could be ready to engrave.

The last step is to convert the image into a 1-bit Black and white image. Converting to a1-bit black and white modifies the dot pattern that is in the image and makes it moresuitable for laser engraving. Of course, you dont have to convert it, but most people

like the converted look on most materials more than the non-converted look.

To convert, click on Bitmaps | Mode | Black and White (1-bit).

To convert, pull down theConvers ion Methodmenuand select Stucki or Jarvis.These two are very similar andmost users cannot tell thedifference. Floyd-Steinberg isalso a good choice.

Adjust the intensity afterselecting the conversionmethod. Most photos will lookbest with an intensity settingbetween 80 and 100.


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In addition to using the dithering processon photographs, you can also use it withClipart. Clipart images that have color or fountain fills can be made more interesting byusing the Jarvis, Stucki, or Floyd-Steinberg dithering patterns.

The ship sample that Epilog uses extensively is a good example:

Your final image willlook like this and youare ready to engrave.

Clipart image before convertingwith a dithering pattern.

Clipart image after converting toa dithered pattern.


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Notes on Pr int ing:

Once you have processed the photo, you are ready to print. In the Epilog Dashboardprint driver there are a couple of settings to pay attention to:

Set your Resolutionin the driver so itmatches theresolution you usedto process yourphotograph.

As mentioned earlier in this procedure, the EpilogDashboard has dithering settings available to use. If youdidnt use Corel to dither your photo you can use theImage Dithering settings in the driver. If you did useCorel to dither your photo, there is no need to set thesame dithering pattern in the driver.

Prep Photos Laser Engraving

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